Expansible mandrel



Dec. 16, 1952 K. E. GRETTVE 2,621,867

EXPANSIBLE MANDREL Filed Aug. 8, 1950 INVENTOR KARL EINAR LAGE GRETTVE',

ATTORNEYJ Patented Dec. 16, 1952 UNITED STATES E ATENT FFICE Application August 8, 1950, Serial No. 178,322 In Sweden February 10, 1950 3 Claims.

Win-ding of paper in roll-s used to be performed on cylindrical paper casings, which are passed over a rotatable driving spindle and are held fast thereon by means of conical plugs, which are driven into the ends of the casing and kept in place by stop screws or the like. The same occurs when paper has to be rolled off from the roll. The said method of driving plugs into the ends of the paper casing may easily destroy the casing, the ends of which crack and cause the casing to slip or entirely come loose. A renewed use of such destroyed casings is impossible.

The present invention has for its object to remedy said inconveniences thereby that the winding casings are held fast upon their driving spindles by an expanding means applied between the spindle and the casing thereby causing a sufiicient friction upon the casing. A device for obtaining said result consists of a cylind-rical bag of rubber or the like, the inner diameter of which suits the diameter of the spindle and the outer diameter is adapted to the inner diameter of the casing, whereby the inner space of the bag is apt to be connected to a source of compressed air for the purpose of expanding the bag between the spindle and the casing so that the casing will be brought along by the spindle by means of friction.

One embodiment of this invention is shown in the accompanying drawing, in which Fig. 1 shows the device applied to a driving spindle, partly in section, and Fig. 2 shows a section along line IIII in Fig. 1.

A bag 3 of rubber is passed over the spindle 2 and consists of two rubber hoses disposed outside each other. The inner hose is provided with a pipe connection 4 with valve 5 for communication with a source of compressed air. The two hoses are then melted together at their ends. Outside the bag, which thus has a cylindrical form inside and outside, an expansion tube 6 of steel or other material is passed over and is provided with longitudinal slits 1. The whole of it is suitably kept together by means of rings 8 which are fixed to the spindle at the ends of the device by means of conical pins 10. The expansion tube 6 is then fixed to the rings by means of knots or pegs 9 on the rings 8 fitting into notches in the ends of the tube.

When the device is to be used, a card board casing (not shown) is passed over it, that is over the expansion tube 6, and compressed air is introduced through the valve 5, so that pressure is applied to the inner of the bag and acts upon the spindle 2 and the expansion tube 6 and therefrom on the card board casing. This casing is then held fast by friction during the winding procedure. When the wound paper roll then is to be removed from the spindle the air is let out from the bag. Since the volume of the bag is quite small, only a small quantity of compressed air has to be used each time. The card board casings remain in completely good condition.

What I claim is:

l. A device for holding a winding casing for paper rolls comprising a spindle, an elongated eiastic cylindrical bag around the spindle, valve and conduit means connected into said bag adapted to introduce compressed air in said bag, an expandable tube surrounding the bag, said expandable tube having open ends and longitudinally extending slits on the periphery thereof inwardly spaced from said ends, and rings fixed to said spindle and contacting said open ends to close the same and maintain the various parts in assembled relationship.

2. A device as claimed in claim 1, and pins securing said rings to said spindle, said rings having portions extending into said open ends, said expandable tube having openings therethrough adjacent said ends and pegs extending through said openings and secured in said rings for fixing said expandable tube to said rings.

3. A device as claimed in claim 2, said spindle having a cut out portion therein extending partly inside the assembled tube and being open outwardly of one of said rings closing said open ends of said expandable tube, said conduit means extending from said bag through said out out portion and beyond said ring in said open portion.

KARL E. L. GRETTVE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,366,999 Campbell Jan. 9, 1945 2,520,126 Collard Aug. 29, 1950 

